Improvement in extracting tan-bark



UNITED STATES S. W. PINGBEE, OF LAWRENCE, MASSACHSETTS.

IMPROVEMENT IN EXTRACTING TAN-BARK.

Specification forming part of Letters Patent No. 41,782, dated March 1, 1864.

To all whom it may concern:

Be it known that I, S. W. PINGREE, of Lawrence, in the county of Essex and State of Massachusetts, have invented a new and Improved Process for Extracting Tan-Bark; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming a part of this specication, in which- Figure 1 represents a sectional plan or top view of the apparatus which I use to carry out my invention. Fig. 2 is a longitudinal vertical section of the same, the line .r Fig. 1, indicating the plane ot' section.

Similar letters ot' reference in both views indicate corresponding parts.

This invention consists in treating` tan-bark, after it has been ground, rst with weak tan liquor or water, whereby the bark is swelled and its strength partially extracted, and exposing the same, after the iirst liquor has been drained off, to the action of steam, which penetrates the swelled bark and prepares it for a second percolation with cold water or weak tan-liquor in such a manner that by the application of the iirst lotion the bark is prepared for the action of the steam, and by the application of the steam the bark is heated and brought inthe best possible condition to give up its tannin to the second lotion of cold water or weak tan-liquor.

In order to execute my invention, I take an ordinary leach-tub, A, which may be divided by partitions a into four or more compartments,each of which is provided with a false perforated or slatted bottom, b. The ground tan-bark is placed in the leach-tub and steeped in weak tanliquor or water for about twelve hours.. By the action of the liquid the bark is softened andswelled, and a portion of the strength ofthe bark is extracted. The liquor thus obtained is drained olf and the bark is exposed to the action of steam. In order to accomplish this object, I'cover the bark up with a suitablecover, B, and admit steam through a pipe, C, which extends over the entire length of the leachtub A. The cover B is perforated with a series of holes, c, which can be closed by slides or other suitable devices, and a tlexible pipe, D, of india-rubber or other suitable material, provided with a metallic mouthpiece, E, conveys the steam through the The mouth-piece E extends down through the bark nearly to the perforated bottoms of the several leaches, and when the bark has been thoroughly heated at one place the mouth-piece is introduced through another of the holes, c, and so on until the bark throughout the entire leach-tub is heated and penetrated by the steam. The tub is then again filled with cold water and allowed to steep for twenty-four hours, (more or less,) when the entire strength is extracted from the bark and the liquor is ready for use.

By this process all the strength is taken from the bark at one heating, the steam penetrates the hard parts of the bark not reached by heating in the ordinary manner, and the cold liquor or water swells the bark and the tannin is readily extracted. Furthermore, a large amount of heating is saved by my process. In the ordinary process of extracting bark the liquid is heated with the bark; but in my process the bark alone is heated and the liquid is poured on cold, and after the bark has been extracted by the ordinary process the liquor has to be left to cool, before it can beused, for several hours, whereas the liquor prepared according to my process is cool as soon as the process is completed and can be used without loss of time.

YI can steep two cords of bark to one'by any process now in use. I can also save one-quarter of the strength of the bark which, by the ordinary process, is burnt or thrown away, and the liquor made according to my process is a better color, and tans or penetrates much faster the gelatine ofthe hide than liquor made in the usual manner.

What I claim as new, and desire to secure by Letters Patent, is-

1. 'Ihe within-described process of extractin g tan-bark by first swelling the bark with water or weak tan-liquor and heating it with steam, and afterward steeping with cold water or weak tan-liquor, substantially in the manner set forth.

2. Introducing steam into the bark contained in a leach-tub, at different points, through a iiexible pipe, D, with a metallic mouth-piece, E, in the manner and for the purpose substantially as specified.

' S. W. PINGREE.

lWitnesses: A

Taos. S. J. DOUGLAS, GEO. W. REED. 

